Support arm



FIG. 1 is a perspective view of a support arm showing my new design;

FIG. 2 is a top view thereof;

FIG. 3 is a right side view thereof, the left side view being a mirror image thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a front view thereof;

FIG. 6 is a rear view thereof; and,

FIG. 7 is a perspective view thereof with additional disclaimed environment showing an in-use position.

The broken-line showing of the circular regions on the top and bottom of the support arm in FIGS. 1, 2, and 4, and of additional supports and a monitor in FIG. 7 is for illustrative purposes only and forms no part of the claimed design. 

CLAIM The ornamental design for a support arm, as shown and described. 